The Coordinated Influence of Indian Ocean Sea Surface Temperature and Arctic Sea Ice on Anomalous Northeast China Cold Vortex Activities with Different Paths during Late Summer

The Northeast China cold vortex(NCCV)during late summer(from July to August)is identified and classified into three types in terms of its movement path using machine learning.The relationships of the three types of NCCV intensity with atmospheric circulations in late summer,the sea surface temperature(SST),and Arctic sea ice concentration(SIC)in the preceding months,are analyzed.The sensitivity tests by the Community Atmosphere Model version 5.3(CAM5.3)are used to verify the statistical results.The results show that the coordination pattern of East Asia-Pacific(EAP)and Lake Baikal high pressure forced by SST anomalies in the North Indian Ocean dipole mode(NIOD)during the preceding April and SIC anomalies in the Nansen Basin during the preceding June results in an intensity anomaly for the first type of NCCV.While the pattern of high pressure over the Urals and Okhotsk Sea and low pressure over Lake Baikal during late summer-which is forced by SST anomalies in the South Indian Ocean dipole mode(SIOD)in the preceding June and SIC anomalies in the Barents Sea in the preceding April-causes the intensity anomaly of the second type.The third type is atypical and is not analyzed in detail.Sensitivity tests,jointly forced by the SST and SIC in the preceding period,can well reproduce the observations.In contrast,the results forced separately by the SST and SIC are poor,indicating that the NCCV during late summer is likely influenced by the coordinated effects of both SST and SIC in the preceding months.

An Extreme Gale Event in East China under the Arctic Potential Vorticity Anomaly through the Northeast China Cold Vortex

Arctic changes influence not only temperature and precipitation in the midlatitudes but also contribute to severe convection.This study investigates an extreme gale event that occurred on 30 April 2021 in East China and was forced by an Arctic potential vorticity(PV)anomaly intrusion.Temperature advection steered by storms contributed to the equatorward propagation of Arctic high PV,forming the Northeast China cold vortex(NCCV).At the upper levels,a PV southward intrusion guided the combination of the polar jet and the subtropical jet,providing strong vertical wind shear and downward momentum transportation to the event.The PV anomaly cooled the upper troposphere and the northern part of East China,whereas the lower levels over southern East China were dominated by local warm air,thus establishing strong instability and baroclinicity.In addition,the entrainment of Arctic dry air strengthened the surface pressure gradient by evaporation cooling.Capturing the above mechanism has the potential to improve convective weather forecasts under climate change.This study suggests that the more frequent NCCV-induced gale events in recent years are partly due to high-latitude waviness and storm activities,and this hypothesis needs to be investigated using more cases.

Influence of Arctic Oscillation on winter climate over China

In this study the relationship between the Arctic Oscillation (AO) and climate in China in boreal winter are investigated. Correlation analysis for the last 41 years shows that the winter temperature and precipitation in China change in phase with AO. High positive correlation (>0.4) between temperature and AO appears in the northern China. High correlation coefficients between precipitation and AO cover the southern China (close to the South China Sea) and the central China (between 30 o -40 o N and east of ~100 o E), with the values varying between +0.3 and +0.4. It is found that during the past several decades the precipitation was strongly affected by AO, but for the temperature the Siberian High plays a more important role. At the interdecadal time scale the AO has significant influence on both temperature and precipitation. Multivariate regression analysis demonstrates that AO and the Siberian High related variance in temperature and precipitation is 35% and 11% respectively. For precipitation, however the portion is rather low, implying that some other factors may be responsible for the changes in precipitation, in addition to AO and the Siberian High.

The current status, threats and protection way of Sanjiang Plain wetland, Northeast China

The Sanjiang Plain is a vast area of alluvial floodplains and low hills in northeast Heilongjiang Province. It is the largest tract of wetlands in China and East Asia outside of Siberia. 28 wetland nature reserves exist on the Sanjiang Plain, and three of them have been listed as wetlands of international importance to water bird conservation by the Ramsar Convention Bureau. The wetlands of Sanjiang Plain are noteworthy for its rich biodiversity, but they continue to decline in area and deteriorate in quality currently. The main threats or constrains, immediate cause, root cause and required response are analyzed in this paper, and the four aspects opinion such as improvement of watershed management, enhancement of protection and restoration of habitats and biodiversity, alternative livelihoods of rural residents living in and near natural wetland reserve, and reinforcement of capacity building of natural reserves are brought forward as the effective measures for the Sanjiang Plain wetland protection.

Association between Arctic autumn sea ice concentration and early winter precipitation in China

Associations between autumn Arctic sea ice concentration（SIC） and early winter precipitation in China are studied using singular value decomposition analysis. The results show that a reduced SIC almost everywhere in the Arctic Ocean, except the northern Greenland Sea and Canadian Basin, are accompanied by dry conditions over central China, extending northeast from the Tibetan Plateau toward the Japan Sea, the Bohai Sea and the Yellow Sea, and wet conditions over South China and North China. Atmospheric circulation anomalies associated with SIC variability show two wave-train structures, which are persistent from autumn to winter, leading to the identified relationship between autumn Arctic SIC and early winter precipitation in China. Given that the decline in autumn SIC in the Arctic Ocean is expected to continue as the climate warms, this relationship provides a possible long-term outlook for early winter precipitation in China.

A comparison of climate changes between Arctic and China in the last 600 years

A compilation of paleoclimate records from lake sediments, trees, ice cores, and historical documents provide a view of China and Arctic environmental changes in the last 600 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic Ocean, Arctic and Greenland and ice cores from the Qinghai-Tibet Plateau, confirming the linkage of environmental changes of different time scales between the Arctic and China. It is shown that the changes of precipitation, temperature and sea ice cover in Arctic were correlated with climate changes in China. This paper also developed a comparative research on the climate changes between Arctic and China both during the Little Ice Age (LIA) and the instrumental observation period. Cycles and trend of temperature variations during LIA and temperature and precipitation during the instrumental observation period are performed. We found some similarities and differences of environmental changes between Arctic and China.

Possible Influence of Arctic Oscillation on Winter Visibility over Eastern China

NCEP/NCAR reanalysis data, the Arctic Oscillation (AO) index and the atmospheric visibility (Vis) data at 134 sites in eastern China (ECN) are used to investigate the possible influence of AO on the wintertime weather and Vis over ECN. A higher relative humidity (RH, compared with the normal year) is identified over ECN in the winters with a positive phase of AO, and the wind anomaly is generally inshore in the coast areas of China. All these processes are consistent with Vis degradation over ECN. On the contrary, in the winters with a negative phase of AO, a lower RH can be identified over ECN, and the wind anomaly is generally offshore, which is favorable for Vis improvement.

A Statistical Linkage between Extreme Cold Wave Events in Southern China and Sea Ice Extent in the Barents-Kara Seas from 1289 to 2017

Arctic sea ice loss and the associated enhanced warming has been related to midlatitude weather and climate changes through modulate meridional temperature gradients linked to circulation. However, contrasting lines of evidence result in low confidence in the influence of Arctic warming on midlatitude climate. This study examines the additional perspectives that palaeoclimate evidence provides on the decadal relationship between autumn sea ice extent (SIE) in the Barents-Kara (B-K) Seas and extreme cold wave events (ECWEs) in southern China. Reconstruction of the winter Cold Index and SIE in the B-K Seas from 1289 to 2017 shows that a significant anti-phase relationship occurred during most periods of decreasing SIE, indicating that cold winters are more likely in low SIE years due to the “bridge” role of the North Atlantic Oscillation and Siberian High. It is confirmed that the recent increase in ECWEs in southern China is closely related to the sea ice decline in the B-K Seas. However, our results show that the linkage is unstable, especially in high SIE periods, and it is probably modulated by atmospheric internal variability.

Advance and key research outputs in China's Antarctic and Arctic science program——commemorating three decades of Chinese National Polar Research Expeditions

The Chinese National Antarctic Research Expedition （CH1NARE） was established and first reached the Antarctic in 1984. Up until 2017, China has undertaken 33 cruises to Antarctica, and seven cruises to the Arctic Ocean. The 30th anniversary of CHINARE was recently celebrated. This thematic issue of Advances in Polar Science contains seven papers reviewing outcomes of polar research during the last 30 years. The results from the CItlNARE research program published in this and subsequent issues reflect the achievements and contributions of Chinese scientists to polar science.

Links between Arctic sea ice and extreme summer precipitation in China:an alternative view

Potential links between the Arctic sea-ice concentration anomalies and extreme precipitation in China are explored. Associations behind these links can be explained by physical interpretations aided by visualisations of temporarily lagged composites of variables such as atmospheric mean sea level pressure and sea surface temperature. This relatively simple approach is verified by collectively examining already known links between the Arctic sea ice and rainfall in China. For example, similarities in the extreme summer rainfall response to Arctic sea-ice concentration anomalies either in winter （DJF） or in spring （MAM） are highlighted. Furthermore, new links between the Arctic sea ice and the extreme weather in India and Eurasia are proposed. The methodology developed in this study can be further applied to identify other remote impacts of the Arctic sea ice variability.

China's climate policy:does an Arctic dimension exist?

The article discusses whether and to what extent an Arctic dimension in Chinese climate policy exists, and whether there are signs of potential linkages between China＇s engagement in the Arctic and its domestic climate policies. Although the Arctic is not directly addressed in domestic climate policy, the article concludes that an Arctic dimension exists, in the following areas： the growing awareness in China of energy-related greenhouse gas emissions, climate risk, resilience and vulnerability, which has contributed to increased attention to climatic change in the Arctic and its impact on China; polar scientific research, which is largely climate related, plays a significant role in determining China＇s Arctic climate agenda; China＇s climate policymaking and domestic institutional set-up is a contributing factor to climate engagement in the Arctic; China＇s status as an observer nation in the Arctic Council might potentially raise the profile of domestic climate policies and lead to the addition of an Arctic pillar to national climate change strategies.

Patterns of international governance in the Arctic and China's approach

The process of rapid change in the Arctic is creating both opportunities and challenges. This paper highlights interactions between different actors in the Arctic in response to multidimensional environmental, political, commercial, and human challenges. It shows that international governance in the Arctic can be characterized by global, multilateral, and regional patterns derived from different mechanisms such as the Arctic Council or the Ilulissat declaration platform, and these interactions are based on common acknowledgment of challenges, mutual interests, and coordinated actions. The paper also examines China＇s participation in international governance in the Arctic. Distinguish from non-Arctic states in a general sense, China as an important stakeholder has both the rights and the capacity to be engaged in multilevel governance patterns. The substantive contribution of China＇s participation--an explorer in scientific cooperation, a pioneer promoting environmental protection, a potential consumer and investor in relation to economic opportunities, and a promoter of local development^are deeply interdepended with the future of development of three ~overnance patterns relatin~ to international ~overnance in the Arctic.

Relationship between Temperature Variation in Winter of China and Arctic Oscillation

[Objective] The study aimed to discuss the relationship between temperature variation in winter of China and arctic oscillation. [Method] By using the NCEP/NCAR reanalysis data, AO index series and monthly temperature data from 160 stations of China, the variation characteris- tics of temperature in winter and AO index series as well as their relationship from 1951 to 2007 were studied. [Result] Temperature in winter of Chi- na correlated positively with AO index series. Both arctic oscillation and winter temperature in China had two major periods of 8 and 18 years. ⅠWTr and ⅠAO series, which had obvious inter-annual and inter-decadal variations, presented the almost same rising trend and had close relationship on an inter-decadal scale. Compared with AO, the Siberia high had more distinguished influences on inter-annual variations of temperature in winter of China. AO might affect changes in the Siberian high and thereby influence temperature in winter of China. AO had a greater influence on tempera- ture in winter of China than the Siberia high on an inter-decadal scale. When the East Asian through was weak, temperature in winter of China and AO index were low, while they were high as it was strong. The impact of AO index on an inter-decadal scale was more significant than the impact on an inter-annual scale. [ Condusien] The research could make the effects of AO on winter temperature of China clear.

China’s Recent Progresses in Polar Climate Change and Its Interactions with the Global Climate System

During the recent four decades since 1980,a series of modern climate satellites were launched,allowing for the measurement and record-keeping of multiple climate parameters,especially over the polar regions where traditional observations are difficult to obtain.China has been actively engaging in polar expeditions.Many observations were conducted during this period,accompanied by improved Earth climate models,leading to a series of insightful understandings concerning Arctic and Antarctic climate changes.Here,we review the recent progress China has made concerning Arctic and Antarctic climate change research over the past decade.The Arctic temperature increase is much higher than the global-mean warming rate,associated with a rapid decline in sea ice,a phenomenon called the Arctic Amplification.The Antarctic climate changes showed a zonally asymmetric pattern over the past four decades,with most of the fastest changes occurring over West Antarctica and the Antarctic Peninsula.The Arctic and Antarctic climate changes were driven by anthropogenic greenhouse gas emissions and ozone loss,while tropical-polar teleconnections play important roles in driving the regional climate changes and extreme events over the polar regions.Polar climate changes may also feedback to the entire Earth climate system.The adjustment of the circulation in both the troposphere and the stratosphere contributed to the interactions between the polar climate changes and lower latitudes.Climate change has also driven rapid Arctic and Southern ocean acidification.Chinese researchers have made a series of advances in understanding these processes,as reviewed in this paper.

China’s policies on Polar Silk Road and impacts on trade and energy use in Arctic region

China has recently established a new policy for the energy use of the Arctic region.Even though it is not a part of the Arctic Council,China has started a series of partnerships with public and private entities of countries that are geographically and politically members of the Arctic polar Circle.The project has to be carried out within the“Belt and Road Initiative”,by establishing new trade routes between China and the rest of the world.The study aims at assessing the fuel consumption for the Arctic shipping routes and comparing them to the traditional ones,in terms of cost reduction and time efficiency.Moreover,a brief consideration on oil&gas arctic fields has been carried out,in order to understand how the energy policy of China is changing the resource utilization.

The People’s Republic of China 2018 Observer Review Report to the Arctic Council

I. China’s contributions to the work of the Arctic Council’s Working Groups, Task Forces, and/or Expert Groups China is geographically a “Near-Arctic State”, one of the continental states that are closest to the Arctic Circle. The natural conditions of the Arctic and their changes have a direct impact on China’s climate system and ecological environment. Having long been involved in Arctic affairs, China is an active participant, builder and contributor in Arctic affairs.

北极海冰对中国西北地区东部主汛期7月降水分布型的可能影响

选取1961-2020年中国西北地区东部154个气象站7月降水、NCEP/NCAR大气再分析及北极海冰资料,利用SVD分解等统计诊断方法,分析了北极关键区海冰对西北地区东部主汛期7月降水主要模态分布型的可能影响途径。结果表明:影响西北地区东部7月降水异常分布型主要有两种海冰模态,一种是当巴伦支海、千岛群岛海域海冰密集度偏小(大),戴维斯海峡海冰密集度偏大(小)时,激发从戴维斯海峡向东南以及从鄂霍次克海向西南方向传播的波列,使得我国西北地区东部上空500 hPa位势高度场距平为“西高东低”(“西低东高”)的分布,造成区域降水异常为“一致偏少(多)”分布型;另一种当波弗特海东海域海冰密集度偏小时,激发从里海东传至鄂霍次克海的波列以及配合我国华南上空的正位势高度异常,使得冷空气路径偏东、偏南以及西太平洋副热带高压偏强,造成研究区降水异常为“北少南多”分布型,反之为“北多南少”分布型。利用“SVD投影法”建立的海冰关键区因子预测模型,其对西北地区东部主汛期7月的降水距平符号的把握及空间分布型具有一定的预测能力,尤其对“区域一致少型”和“北多南少型”的预测效果较好。

美国情报界对华威胁认知论析--以《美国情报界年度威胁评估》报告为分析对象

[研究目的]分析美国情报界对中国的威胁认知与评估,有助于理解美国对华战略竞争及其未来前景,为维护我国国家安全具有重要意义。[研究方法]以历年《美国情报界年度威胁评估》报告为分析对象,采用案例研究法和文献分析法,探讨美国情报界对华威胁认知、影响因素、危害后果与中方应对。[研究结论]随着美国外部安全环境和中美关系的变化,美国情报界日益视中国为“首要威胁”,对中国国家利益构成愈加严峻的挑战。中国应基于对美国情报界对华威胁认知趋势及其危害的全面分析,制定应对之策。

当前中国北极权益面临的风险及其化解路径——以北极地缘政治博弈为分析视角

俄乌冲突的溢出效应引发了俄罗斯与北极七国在北极地区激烈的竞争。现今北极地区呈现出安全竞争加剧、经济合作受阻、合作框架遭到破坏等地缘政治博弈新态势。北极竞争的加剧使得我国战略安全受到威胁,国际形象遭受损害,公海活动空间遭受挤压,所倚仗的北极治理机制面临重塑。这些问题给我国北极权益维护带来了新的风险。我国应当深化利益认知、提升治理能力,以公域科学考察为切入点,保持并深化同北极国家间的合作,同时强化北极话语建设,成为北极事务的积极参与者、建设者和贡献者。